The deployment of restraint devices in a motor vehicle appropriate to an accident is known. An emergency call may be transmitted. The reduction of speed during an accident may be used as a criterion for the severity of an accident.
German Patent No. 199 45 614 describes a method for transmitting data between a control unit for restraining devices and sensors, where it is possible for the control unit to flexibly and temporally access the measuring data of individual sensors. In this context, a control unit transmits a request telegram to the sensors, each sensor being able to deduce from the comparison of the request telegram with its own address, whether or not, and in which time window, it should transmit its measuring data to the control unit. German Published Patent Application No. 197 48 992 describes a device for emitting emergency signals from a motor vehicle, the device having a microcomputer, which dispatches an emergency call as a function of sensor signals. In this case, it is possible to consider the severity of the crash. In German Published Patent Application No. 199 05 193, a method for triggering a safety device in a motor vehicle in the case of a rollover is described, the triggering decision being made as a function of rotation-rate data and inclination angles of the vehicle.
The method of the present invention for classifying a rollover event of a motor vehicle has the advantage that it is possible to determine the severity of an accident in a simple manner even in a rollover event, an emergency call then being transmitted as a function of this recognized accident severity. A prerequisite for this is that restraint devices are used. Thus, the emergency call contains the accident severity as its content. The rotation rate, which may be detected with a rotation-rate sensor, is one of the parameters to be analyzed, because the accident severity increases in a rollover event as the rotation rate increases since this indicates a very rapid rollover event. However, the rotation rate and the rotational angle, which is derived from the summed rotation rate, ultimately determine the classification of the rollover event as a pair of values. The rotation rate is suitable to record rapid events in particular, while the rotational angle characterizes the rollover event per se. Both parameters are thus used for classification. From this are then derived the pairs of values which result in a classification of the rollover event in a diagram. The classification takes place, however, only if a deployment decision for the restraint devices has been made.
It is advantageous in particular that the rollover event is recognized on the basis of the impact energy or impact momentum. In the case of impact energy, the kinetic energy, which characterizes the rotation rate and the potential energy, which characterizes the rollover event per se in particular, is taken into account. Moreover, it is of advantage that the summed rotation rate is compared with threshold values in order to finally perform the classification. In a rotation rates-rotational angle diagram, the class areas for the pairs of values are then defined by establishing zone boundaries corresponding to the threshold values. Thus, if a pair of values lies in such a class area, it is then classified according to that class area.
Moreover, it is advantageous that a device to implement the method is present, which has a rotation rate sensor to detect the rotation rates, a processor to analyze the rotation rates and to sum the rotation rates, a transmitter to transmit the emergency call, an acceleration sensor to determine an impact energy and a memory to temporarily store interim results and to call specified threshold values.